1. Field of the Invention
The present invention relates to a method for the washing of laundry in a motor-driver washing machine. More particularly, the laundry method pursuant to the invention is intended to optimize the washing procedure with respect to the amount of energy which is needed in order to achieve the desired cleaning effect.
According to the invention it is intended to define the mechanical energy acting on the laundry during the washing cycle. This mechanical energy in a vertically rotating drum of the washing machine is induced into the laundry by an arm additionally rotating the agitator for the fluid flow; and in the case of a washing machine equipped with a horizontal rotating drum, it is introduced mainly by the successive lifting and falling movements of the laundry within the drum; in effect, the mechanical energy as actually introduced herein primarily depends upon the filling rate of the drum.
Inasmuch as the introduced mechanical energy is an equivalent to the electrical energy assumed by driving motor of the drum in the case of a vertically rotating drum, the mechanical energy may be measured by measuring the electrical energy which has been consumed during the washing cycle. In the case of the horizontal rotating drum; however, there has to be taken into account the filling degree of the drum, and additionally, to obtain the mechanical energy which has acted onto the laundry during the washing cycle.
2. Discussion of the Prior Art
In order to evaluate the actual filling of the drum, the German Patent Publication DE 44 31 846 A1 describes a method of operating which is driven, on the one-hand, at a constant speed of rotation and on the other hand, with a constant angular acceleration and torques which are to be, respectively, applied by the drive motor for this purpose, are then compared. That comparative measurement serves to determine the imbalance of the drum in order to ascertain therefrom the maximum possible speed of rotation in the spin or centrifuging mode.
However, that procedure for determining the drum loading is expensive inasmuch as the drum which is laden with laundry must first be run for a certain period of time in two different modes; such as a constant speed of rotation and a constant angular acceleration, and the torques which are to be respectively applied by the motor in that instance must be determined and ultimately evaluated.
Accordingly, it is an object of the present invention to quickly and easily detect the loading of a horizontally rotating washing drum by taking it into account in the implementation of a washing program based on constant mechanical energy which is to be introduced into the laundry, since this energy depends upon the actual load filling of the horizontally rotating laundry drum.
According to this object, inventively, if the power draw of the electric motor which drives the washing drum is measured, then the drum loading can be inferred therefrom. In the event that the washing drum is fully laden, the electric motor only has to overcome friction and, upon acceleration must overcome the mass inertia, and therefore only draws a comparatively small amount of power. If, on the other hand, the drum is not fully laden (for example; is only half-full) the motor must then convey the entire wash upwardly against the force of gravity before it drops down again, without in the case as would be the instance with a fully loaded drum, with the impetus or momentum being transmitted back to the washing drum. As a consequence, the electric motor requires an overall higher level of power, and for that reason its power draw is comparatively considerably high.
Basically, the primary concept underlying the invention resides in that the laundry, in order to obtain a constant remaining washing result, has imparted thereto a uniformly remaining or constant quantity of mechanical energy. This of a particularly practical interest for washing machines with horizontally rotating drum which are filled to considerably different degrees. At a full loading the laundry is located in a packed manner in the drum and rotates in conjunction therewith. In contrast therewith, at a lower amount of loading, the individual laundry pieces are raised with the rotation of the drum so as to again fall down under the effects of gravity. Consequently, at a lower degree or amount of loading, a higher mechanical energy acts on the laundry, and the washing procedure can be either shortened or maintained through lengthier pauses (such as in the course of a periodic switching over of the direction of rotation) to a constant duration however at a reduced mechanical energy effect.
In addition to the foregoing, the invention is also directed to washing machines with vertical rotating drums, in which an agitator causes a flow of water through the laundry, and additionally a rotating arm maintains the laundry in motion. Also, in this instance, does the degree of filling of the drum influences the mechanical energy which is introduced into the laundry; when concurrently the dominating influence originates here from the duration of operation of the rotating arm; in effect, from an additional aspect which can be directly measured through the power pick-up of the electrical drive motor.
Used as a measure for the degree of cleaning, in effect, as a measure of the mechanical cleaning power which is introduced to the laundry pieces, for horizontal washing drums there is initially employed the electrical power which is received by the drive motor for the drum, which can be measured without any problem and at regulated drives is already available as a measurement value. This measuring procedure, as such, is not the inventive aspect itself, but rather the time of limitation or gap in the washing process in that, at the end of a washing process independently of the momentary of the loading of the drum there always acts the same mechanical energy on the laundry.
The power draw of the electronic motor can be detected during the normal washing phase, or also when the motor is being accelerated up to a predetermined speed of rotation is being maintained. The step of determining the power draw is effected by measuring the motor current, the motor speed and the electric voltage applied to the motor. The power draw is that from the power mains or the power which is outputted by the electronics for motor control.
With a possession of knowledge over the power losses which occur, the mechanical power acting on the laundry in the drum can be determined from the power draw of the electronic motor. With a higher level of power draw on the part of the motor, a higher level of mechanical power is also transmitted to the laundry. Thus, if now the loading of the washing drum and the mechanical power acting on the laundry were known by virtue of ascertaining the power draw of the electronic motor, the operating procedure of the washing program would be of such a configuration that the laundry, or a predetermined amount of laundry, is throughout the entire washing program always acted upon with substantially the same predeterminable mechanical energy irrespective as to whether the washing drum is or is not full.
In modern household washing machines, the washing program often starts with displaying the time needed for the individual washing program which was actually selected. In order to keep this time independent from the actual loading of the horizontal rotating drum but with a given and constant mechanical power acting on the laundry, the drive interruptions of the turn or between reversed turns of the drum may be increased or shortened in their periods of time, depending on the actual load. With a vertical rotating drum; however, the turn speed of the rotating arm may be varied according to the load of the drum in order to keep the originally indicated washing time with a predetermined integral of mechanical energy induced into the laundry during the washing time.
The invention is described in grater detail hereinafter by means of examples. Even through the examples are generally applicable to both types of washing machines (with horizontally rotating drum and with vertical rotating axis of the drum), the latter case is the preferred one in the description set forth hereinbelow.